(a) Field of the Invention
The present invention relates to a column driver and a flat panel display having the same.
(b) Description of Related Art
Generally, flat panel displays (“FPDs”) convert digital image data such as R, G and B from a host computer into analogue data to display desired gray scale or color image.
FIG. 1 is a block diagram of a conventional flat panel display.
Referring to FIG. 1, the FPD 1000 includes a flat panel assembly 1100, column drivers 1200, gate drivers 1300 and a signal controller 1400.
When the flat panel assembly 1100 has, for example, resolution of XGA grade (1024×768), the flat panel assembly 1100 includes 3,072 (=1024×3) data lines (not shown), 768 gate lines (not shown), a plurality of switching elements (not shown) and a plurality of pixels (not shown). Such structure is generally referred to as an active matrix structure.
The column drivers 1200 convert the digital image data from the signal controller 1400 to analogue data voltages which are transmitted to the pixels via the data lines. In FIG. 1, the column drivers 1200 have called a single bank structure formed on one side of the panel assembly 1100.
The gate drivers 1300 turn on the switching elements in a row simultaneously such that the analogue data voltages driven by the column drivers 1200 are applied to the pixels connected thereto.
The signal controller 1400 receives the digital image data and control signals from a host computer (not shown). In detail, the signal controller 1400 receives the digital image data and the control signals from the host computer in a general digital interface scheme, e.g., a low voltage differential signaling (“LVDS”) scheme.
Further, the signal controller 1400 includes an LVDS receiver 1410, a timing generator 1420 and a reduced swing differential signaling (“RSDS”) transmitter 1430.
The LVDS receiver 1410 receives the digital image data and the control signals from an external device. The timing generator 1420 converts the control signals into a plurality of control signals suitable for the column drivers 1200 and the gate drivers 1300. The RSDS transmitter 1430 converts the digital image data and the control signals of the LVDS scheme into those of the RSDS scheme for transmittance to the column drivers 1200.
FIG. 2 is a conventional operation timing chart and FIG. 3 is a drawing to illustrate the formats of digital image data of an RSDS scheme.
Referring to FIGS. 2 and 3, if the digital image data is signals of 6 bits, respectively, the signal controller 1400 transmit the digital image data and the control signals via three pairs of signal lines (not shown) for each of RGB and a pair of clock lines (not shown). In detail, the signal controller 1400 transmits them to the column drivers 1200 via nine pairs (=three pairs×RGB) of the signal lines and a pair of the clock lines.
FIG. 4 is a detail block diagram of a column driver of an RSDS scheme.
Referring to FIG. 4, the column drivers 1200 includes an RSDS receiver 1210, a shift register 1220, a data register 1230, a data latch 1240, a D/A converter 1250 and an output buffer 1260.
The RSDS receiver 1210 receives the digital image data of the RSDS scheme from the signal controller 1400. The shift register 1220 gets the digital image data to be loaded from the data register 1230 to the data latch 1240 at a time. The signal controller 1400 transmits the digital image data to the column driver 1200 until all the latches of the data latch 1240 are filled with the data. The signal controller 1400 also transmits the digital image data to the column driver 1200 until all the row data are loaded. Subsequently, the column driver 1200 loads the digital image data loaded to the data latch 1240 to the D/A converter 1250. The D/A converter 1250 converts the digital image data into the analogue data voltages. Thereafter, the output buffer 1260 applies the analogue data voltages to the respective data lines of the panel assembly 1100.
Typically, the FPD transmits the digital image data and the control signals via a plurality of signal lines and clock lines. Such form of transmission has problems that power consumption and electromagnetic interference (“EMI”) increase.